This invention relates to coupling or connector devices for hoses and conduits and more particularly to an improved coupling for interconnecting flexible conduits such as plastic hose or tubing, as used in irrigation systems.
In one common form of drip irrigation system water is supplied from a central source through thin-walled plastic tubing to a multiplicity of in-line emitters which allows for a drip-like flow of water or to similar side branching emitters connected to a tee-type fitting. The emitters are spaced apart at predetermined intervals in the conduit so as to be at or near the roots of the plants being irrigated.
As shown in U.S. Pat. No. 3,693,657, most emitters heretofore devised had extended barb-type connector portions to facilitate their connection with the water carrying conduit or plastic tubing. Although such barb-type connectors were used extensively they had several serious disadvantages. In the first place the barb connector was designed to have a significantly larger diameter than the inside plastic conduit diameter. Thus, the standard procedure for installing an emitter required that the end portion of the conduit or tubing be heated so that it would expand slightly while being forced onto the barb. Where many hundreds or even thousands of emitters are installed in a typical drip irrigation system, this necessity to heat the conduit in order to connect it to an emitter or fitting entailed a substantial amount of added time and labor. Moreover, once installed, the plastic conduit as it cooled, was under a constant tension stress. Over a period of time this stress often caused a tendency for the conduit to crack and eventually this stress-cracking caused a failure or leak. A further disadvantage with the prior art barb-type connectors arose when it became necessary to remove or replace an emitter which may have become clogged or otherwise inoperative. Heretofore, it was necessary to cut the conduit or tubing near the emitter and then reheat the conduit end portion in order to re-connect it to the new emitter. This procedure was not only time consuming but also wasteful of conduit.